CERN ELMB
CERN ELMB (Embedded Local Monitoring Board) is a multi-function device that is focused on providing analog inputs/outputs, digital inputs/outputs, SPI connectivity and custom functionality, being controlled by CANbus.
Currently, at CERN, it is used by:
- ATLAS Experiment
- CMS Experiment
- LHCb Experiment
- ALICE Experiment
- TOTEM Experiment
The total count of ELMB in operation at CERN is of around 10000.
ELMBs have been carefully tested for operation under radiation.
The main group behind ELMB is Atlas Central DCS.
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Front
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Specification
ELMB
Please see Annex B. of ELMB User Guide in "Documents" tab for source.
AVR RISC architecture ATMEL Atmega128*
- 128 Kbytes of on-chip flash memory,
- 4 Kbytes of SRAM,
- 4 Kbytes of EEPROM,
- In-System Programming via CAN bus
Peripheral Features - Full CAN controller interface with PCA82C250
- 6 bit CAN identifier and 4 baud rates supported
- 3-wire SPI interface
- Real Time Counter with a separate 32 kHz crystal
- Timers
- 8-channel 10-bit ADC I/O lines available2
- 6 external interrupt inputs
- Port A 8 digital bi-directional I/O lines (can alternatively be used for external SRAM).
- Port C 8 digital output lines (can alternatively be used for external SRAM).
- Port D 5 digital bi-directional I/O lines
- Port E 5 digital bi-directional I/O lines
- Port F 8 digital input lines or 8 analog inputs for the ADC
- Strobe and enable lines for external SRAM
Power regulators - Separate regulator for the CAN bus transceiver and optocouplers
- Regulator for the microcontrollers
- Voltage converter 3.3V to 5.4V
Optional Delta-sigma ADC CRYSTAL CS5523 with 64 channel multiplexer - 6 bipolar or unipolar input ranges from 25mV to 5V
- 100 pA input current on 25mV, 55mV and 100mV
- 10nA on 1V, 2.5V and 5V ranges
- 8 conversion rates from 2 Hz to 100Hz
- 64 channel multiplexer
- +5V and -5V on board power regulators
Mechanical dimensions - The size of the printed circuit board is 50x67mm.
- The board is equipped with two connectors with 100 pins.
Motherboard specification
Please note that in known designs ELMBs get plugged in into:
- "the" ELMB motherboard, which is shown in "ELMB128 Documentation" document
- less known motherboards, with ELMB's connector being central part, often experiment specific
- other types of boards, in which ELMB plays only secondary role, here Alfa-R local controller could be a good example
Radiation tolerance specification
Detailed figures are available in Fernando Varela Rodriguez's thesis, chapter 4.1. The thesis is available in "Documents" tab.
Common use case
In most cases ELMBs are part of a system that is composed at least of:
- Local Control Stations, which are computers running SCADA software and which are interconnected to form a global distributed control system
- Fieldbuses (CANBus in case of ELMB)
- ELMBs
- Analog or digital sensors and actuators such as: temperature,
humidity, radiation sensors, switches, voltage and current monitoring
modules, solid state relays,
Sources of information about ELMB
- https://twiki.cern.ch/twiki/bin/view/Atlas/DcsElmb - Atlas Central DCS Wiki on ELMBs
- http://edms.cern.ch EDMS (look for: ELMB)
- http://www.nikhef.nl/pub/departments/ct/po/html/ELMB/ELMBresources.html Henk Boterenbrood (author of ELMB's embedded software) webpage on NIKHEF pages
- Fernando Varela Rodriguez thesis (available on this page in "Documents" section) (alternatively, you can find it on http://cds.cern.ch)
- this page
User documentation
https://www.ohwr.org/project/cern-elmb/uploads/3f5778c0823c590cdb1499d098d0d91f/ElmbUserGuide.pdf ELMB's user guide
Developer docs
https://www.ohwr.org/project/cern-elmb/wikis/Documents/CANopen-high-level-protocol-for-CAN-bus CANopen high-level protocol for
CAN-bus
https://www.ohwr.org/project/cern-elmb/wikis/Documents/CANopen-Application-Software-ELMBio- CANopen Application Software ELMBio
Radiation tests
https://www.ohwr.org/project/cern-elmb/uploads/2bd9d5687aac1e3f038e5dad0500f17c/thesis-2002-035.pdf See chapter 4.1